Manufacture of commutator bars



Nov. 23, 1954 c. CLEVENGER MANUFACTURE OF COMMUTATOR BARS 2 Sheets-Sheet1 Filed Aug. 29, 1950 Nov. 23; 1954 c. CLEVENGER MANUFACTURE OFCOMMUTATOR BARS Filed Aug. 29, 1950 2 Sheets-Sheet 2 9&2! v Ef /f UnitedStates Patent "ice lVlANUFACTURE OF CGNIMUTATOR BARS Carl L. Clevenger,Anderson, Ind., assignor to General Motors Corporation, Detroit, Mich.,a corporation of Delaware Application August 29, 1950, Serial No.182,012

1 Claim. (Cl. 78-60) This invention relates to the manufacture ofcommutator bars having dove-tail tangs and its object is to provide amethod and apparatus for producing them economically without waste ofmaterial. To accomplish this object, I provide for use with a two-blowheader apparatus comprising a die-holder adapted to be attached to afixed part of the header, a die supported by the holder and having anopening for receiving two segments of bar stock of keystone crosssection and to locate them in definitely spaced, parallel relation withtheir thinner edges facing one another, the segment receiving opening inthe die being bounded by surfaces which are engageable respectively withthe thicker edges of the segments and with the side surfaces thereof toprevent separation of the segments and to prevent thickening thereof,punches of cross sectional contour adapting them to be received by thedie and having tang forming end surfaces between which the material ofthe segments between their thicker edges is squeezed and is caused toflow into the space between the segments, the material of one segmentflowing toward the material of the other segment and into contacttherewith whereby the displaced material is caused to conform to thetang shaping surfaces of the punches, one of the punches being supportedby the die holder for movement of the operating end thereof from aposition near the inner end of the die to a position beyond the outerend of the die to eject the formed commutator bars, said punch beingaligned, when the die holder is mounted on the header, with the ejectorrod of the header which operates to effect said movement of said punch,and a holder for the other punch adapted to be mounted on the headerslide which the header ram supports for movement laterally of theslide-supported punch, said slide being operated by the header to alignthe slide-supported punch in alignment with the die and the ram beingoperated by the header to move the punch into the die to cause thesegments to be squeezed by said punch against the holdersupported punch.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings wherein a preferred embodiment of the present invention isclearly shown.

in the drawings:

Fig. l is a longitudinal sectional view of the header operated apparatusin open position preparatory to receiving two segments of bar stock.

Figs. 2, 3 and 4 are views similar to Fig. 1 showing the steps offorming the pieces in the commutator bars.

Fig. 5 is a fragmentary sectional view on line 55 of Fig. 1.

Fig. 6 is a view in the direction of arrow 6 of Fig. 1.

Fig. 7 is a view in the direction of arrow 7 of Fig. 1.

Fig. 7a is a fragmentary detail view of plate 54.

Fig. 8, like the succeeding figures is drawn to a larger scale thanFigs. 1 to S and is a sectional view on line 8-8 of Fig. 1.

Fig. 9 is a sectional View on line 99 of Fig. 1.

Fig. 10 is a sectional view on line lil1tl of Fig. 1.

Fig. ll is a sectional View on line ll.11 of Fig. 1.

Figs. 12 and 13 are respectively plan and end views of a member whichguides bar stock into the header.

Figs. 14 and 15 are respectively side and end views of a segment of barstock before forming.

a commutator bar formed by the machine.

2,624,952 Patented Nov. 23, 1954 Referring to Fig. l, the header withwhich the described apparatus is used provides a fixed support 20 and amovable slide 21 carried by the header ram (not shown) which the headermechanism causes, twice in one cycle, to advance toward and retract fromthe support 20. Between reciprocations of the ram, the header causes theslide to move transversely of ram movement to cause punches carried bythe slide 21 to be successively aligned with a die attached to thesupport 20. A die-holder block 22 attached to the support 20 provides aguide for a sleeve 23 retained by a pin 24 which, as shown in Fig. 5, isreceived by a groove 25 of the sleeve 23 so that sleeve 23 may havemovement relative to block 22. Sleeve 23 supports a die 26 which is madein four parts comprising two parts 27 (Fig. 10) and two parts 28 whichare assembled together and which provide, when assembled, a taperingexterior surface adapted to fit into a tapered bore in the sleeve 23whereby when they are forced into the sleeve 23 they are retained inassembled relation. As shown in Fig. 10, the die holder block 22 is madein two parts 22a and 2212 which are secured together. The space 29between parts 27 receive forming punches to be described.

A forming punch 30 received in space 29 is fixed at one end by rivets 31(Fig. 8) to two cylindrical segments 32 which are received within a bore33 of support 20 which receives also an ejecting rod 34 which isoperated in one direction by the header mechanism to eject the formedbars. As viewed in Fig. 1 the movement imparted by the header mechanismto the rod 34 is upwardly and motion of the rod 34 in the oppositedirection is effected by movement of the punch 39.

Referring to Fig. 9 punch 30 is received between semicylindricalsegments 35 which together provide a bushing 36 (Fig. 1) having a flange37 and received by a sleeve 38 which is guided by the block 22. Theblock 22 encloses a spring 39 located between sleeves 23 and 38 whichurges these parts respectively against stop pin 24 (Fig. 5) and fixedsupport 20.

Referring to Figs. 1 and 6 the slide 21 carries a punch holder plate 40attached thereto by studs 41 and nuts 42. Plate 49 carries a bushing 43comprising halves 43a and 43b assembled by screws 44 with a pusher bar45 having the same cross sectional contour as punch 30 whereby bar 45can be received in the space 29 in the die 26. Plate 40 carries abushing 46 comprising halves 46a and 46b assembled by screws 47 with apunch 48 as shown in Fig. 11. To provide clearance for the bar 45 andthe punch 43 the block 22 is provided with recesses 49 and 50respectively.

The block 22 and also the support 20, as indicated in Figs. 7, 12 and13, support a guide 51 made in two parts 51a and 51b and providingcylindrical holes 52 into which bar stock is fed by the stock feedingmechanism of the header, said bar stock being guided into holes 53 ofkeystone cross-sectional contour. This feeding mechanism moves the barstock through the holes 53 and against a fixed stop (not shown) spaced adistance from the surface 51s of the guide 51 equal to the lengthrequired for making the commutator bar. The ends of the bar stock liebetween the edge of a plate 54 and retaining clips 55 secured to theplate 54. The header includes mechanism (not shown) for moving the plate54 upwardly, as seen in Fig. 7, and during this movement the edge ofsuch plate cooperates with the end suface 51s of the guide 51 to shearof? segments S (Figs. 14 and 15) of a length suitable for makingcommutator bars.

After these segments S have been sheared, the upward movement of plate54 continues until the segments are moved to a position in alignmentwith recess 29 (Fig. 10) of the die 26.

The slide 21 is caused to move from the position shown in Fig. l to thatshown in Fig. 2 to cause bar 45 to push the segments S into the die 26and against the punch 30 which can then move only from the positionshown in Fig. l to that shown in Fig. 2 due to the fact that the ejectorrod operating mechanism of the header has then retracted to a positionsuch that the rod 34 can move only from the position shown in Fig. l tothat shown in Fig. 2.

Therefore the segments S are caused to be shaped by the punch 30 asshown in Fig. 2.

The slide 21 is then retracted from the position shown in Fig. 2 to thatshown in Fig. 1; and then is moved laterally to the left to align thepusher bar 45 with recess 49 of block'22 and to align the punch 48 withthe punch 30. Then the slide 21 moves into the position shown in Fig. 3to cause the segments to be formed into commutator bars B. During thisfinal step of bar formation each bar B is provided with a dove-tail tangt (Fig. 16). The deformation of the segments S to form these tangscauses material of the segments to be forced against one another withpressures that are substantially equal and opposite so that the strainon the punches is minimized. This deformation causes the segments 13,which are confined by the die 26 so as to prevent appreciable separationthereof and increase of thickness thereof, to press on the die 26 andthereby to create considerable frictional resistance to movement of thesegments relative to the die 26. Therefore, during movements of thesegments S with respect to the punch 30 for a distance substantiallyequal to the distance between the lower ends of the segments (Fig. 2)and the shoulders 30a of the punch 30, the die 26 moves with thesegments, said movement beingopposed by the spring 39 as the sleeve 23moves from the position shown in Fig. 2 to that shown in Fig. 3, andsaid movement being permitted by the groove 25 (Fig. 5) which receivesthe pin 24. Since the die 26 moves with the segments as they are beingformed into the bars B, Wear on the die 26 is substantially reduced.During the formation of the dove-tail tangs t, the material of thesegments flows toward one another and into contact. Because further flowtoward the center of the die is resisted, the material of the segmentsis caused to take on the shape of the ends of the punches. As thematerial forming the dove-tail tangs come together, the pressures whichthey apply to one another are equal and opposite thus substantially reducing strain on the die and punches.

Following the operation shown in Fig. 3 the slide 21 moves to theposition shown in Fig. 4 as the ejector rod 34 moves toward the slide 21to force the punch 30 and the bars B out of the die 26. The separationof the punch 48 from the punch 30 is such that the bars are releasedfrom the punches so that they may gravitate into a hopper. As the rod 34is moved to ejectthe bars, the cylindrical parts 32 are caused toengagethe bottom, as seen in the drawings, of segments 35 which form thebushing 36, thereby causing the sleeve 38 to move from the positionshown in Fig. 3 to that shown in Fig. 4 whereby the spring 39 iscompressed to cause return of die 26 to normal position. When theejector operating mechanism of the header retracts from the rod 34, thespring 39 expands to move the bushing 38 downwardly, as seen in thedrawings, to the position shown in Fig. 1. Duringthis downward movementthe bottom of bushing 36 engages the cylindrical parts 32' to which thepunch 30 is attached and causes the punch 30 to-return to the startingposition shown in Fig. 1.

Thus two segments S are formed simultaneously into two bars B by causingthem to be located within a die while the punches 30 and 48 havingshearing blades30b and 48b respectively cut into end portions of thesegments to provide the dove-tail tangs t of the bars. The shoulders 30aand 48a of punches 30 and 48 respectively approach each other to suchdistance that the spacing between these shoulders is thesame as thelength of the segments S. It is not the purpose of these shoulders toexert a deforming pressure upon the Segments S, but merely to confinethe ends of the segments while other portions are being deformed to makethe dove-tail tangs. Therefore during formation of these tangs thelength of the bars remains substantially the same as that of thesegments. Therefore the. length of the bars is uniform and the tangs arelocated a uniform distance from the ends of the bars.

While the embodiment of the present invention as herein disclosedconstitutes a preferred form, it is to be understood that other formsmight be adopted.

What is claimed is as follows:

A die assembly including a die, a die holder having a recess forreceiving the die and Within which the die has movement relative totheholder from a normal position to a position closer withinthe recessduring operation, a passage in said die and die holder, an articleejecting punch in said passage, a member within said recess having anopening in which the punch is positioned, a spring in said recesspositioned between said member and the die, and urging the member towarda fixed part of the holder and the die away from said fixed part tonormal position, a stop arresting movement of the die away from saidfixed part, and means operable by the ejecting punch as it moves towardejecting position to move said member in the same direction so as tocause the spring to be additionally stressed to force return of the dieto normal position, said spring operating to effect return of theejecting punch to its initial position after movement of said punch toits ejecting position.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,402,919 Carlson Jan. 10, 1922 1,457,801 Van Dusen Jan. 5,1923 1,690,917 Wilcox Nov. 6, 1928 1,693,997 Carter Dec. 4, 19281,898,696 Sorensen Feb. 21, 1933 2,042,375 Abel May 26, 1936 2,122,874Whipple July 5, 1938 2,253,003 Whipple Aug. 9, 1941 2,360,528 TalmageOct. 17, 1944 2,411,379 Langhammer Nov. 19, 1946 2,549,642 Seelig Apr.17, 1951 FOREIGN PATENTS Number Country Date 199,109 Great Britain June13, 1923

